2.4 Experimento

1.1        2.4 Experimento

Conociendo el grosor del film obtenido se depositaron 3 muestras de 4, 11 y 15 nanometros de carbono la mas delgada es la 771, la siguiente 772 y la mas gruesa 773

a)b)

c)

Optic microscopy of thin films as deposited a)771 4nm. b)772 11nm. c)773 15nm. Rougness and splashing can be appreciated on these thin films, appearing more frequently on filmes gruesos, qe en los delgados.

Estos filmes se sometieron a anneado a 1470 grados centígrados durante 50 segundos  , en capsulas de cuarzo, con atmosfera de argón y presión constante de 1 atm.

Foto de la cámara del telefono

1.1.1        2.4.2 Raman. Espectro característico.

Se hizo la lectura de espectro Raman para las tres muestras.  El espectro Raman se dividio en secciones para su análisis:

1.1.1.1         2.4.2.0 SiO2

Estos picos corresponden a cristobalita y cuarzo (se sabe que el SiO2 recristaliza a temperaturas superiores a 800 grados centigrados). En las graficas se observan  tambien los picos caracteristicos del Silicio Cristalino, cuya principal frequencia se ve atenuada, dependiendo del grosor del film de carbon depuesto .

a)b)

c)d)

a) Si/SiO2 Raman region of 771 sample. b) sample 772. c) sample 773. d) Raman Spectra from SiO2 cristobalite and quartz, from early investigations.

Fig. 5 Raman spectra for bulk Si, Si NPs, Si NSs, and Si NRs. The inset figure is an enlargement of the peaks framed in dotted rectangle.

Formation mechanism and optical characterization of polymorphic silicon nanostructures by DC arc-discharge
July 2015RSC Advances 5(84):68714-68721
DOI: 10.1039/C5RA11738K
Jieyi YuJian GaoF.-H XueF.-H XueShow all 10 authorsGuozhong CaoGuozhong Cao

https://www.researchgate.net/publication/282526534_Formation_mechanism_and_optical_characterization_of_polymorphic_silicon_nanostructures_by_DC_arc-discharge

1.1.1.2         2.4.2.1 SiC

Se observa la presencia de 3С-SiC en estos picos caracteristicos.

a)b)

c)

Presencia de 3C-SiC en las tres muestras con diferentes tiempos de deposición de film de carbono. Dado el tiempo de anneado igual para las tres muestras, la intensidad de los picos correspondientes a 3C-SiC es la misma

​Figure 2 shows a representative Raman spectra from a SiC film on Si (111) measured at the void and outside the void. The feature seen in the range 900–1100 cm⁻¹ is associated with second-order Raman scattering from the Si [15]. The characteristic transverse optical (TO) and longitudinal optical (LO) phonon modes are observed at ~794 cm⁻¹ and ~968 cm⁻¹, respectively. This confirms that the SiC layers analysed in this work mainly consist of a cubic polytype structure [5,16].
A low intensity shoulder, clearly observed at ~764 cm⁻¹ near the TO band, indicates the presence of a small amount of the 6H-SiC polytype in this SiC layer. From Fig. ​2a and ​2b, the TO peak at 794 cm⁻¹ demonstrates asymmetry from the low-frequency side. At the same time, in accordance with Nakashima [5], structural disorder in the SiC leads to a symmetrical widening of all the TO peaks. We conclude that the observed asymmetry of the TO peak is due to the presence of a 6H-SiC peak at ~789 cm⁻¹, clearly demonstrated by fitting of the TO band in Fig. ​Fig.2b.2b. From the fit, the linewidth of the band at ~794 cm⁻¹ is approximately ~7.8 cm⁻¹. This is 2.5 cm⁻¹larger than that for relaxed 3C-SiC on a 6H-SiC substrate in Ref. [17]. 

https://www.researchgate.net/publication/258424685_Nanocatalytic_Growth_of_Si_Nanowires_from_Ni_Silicate_Coated_SiC_Nanoparticles_on_Si_Solar_Cell/figures?lo=1

Nanocatalytic Growth of Si Nanowires from Ni Silicate Coated SiC Nanoparticles on Si Solar Cell
September 2013 Journal of Nanoscience and Nanotechnology 13(9):6189-95
DOI: 10.1166/jnn.2013.7691
Bhaskar Parida, Jaeho Choi, Hyung Yong Ji, Keunjoo Kim

Fig. 4. Raman spectra of (a) the microtextured Si solar cell coated with SiC nanoparticles and (b) the annealed Si solar cell with the formation of Si nanowires at 1100 C under a H 2 ambient atmosphere.

2.4.2.2 Carbono

Especial interés presenta el sector correspondiente al carbono, donde es evidente la diferencia  en los niveles de intensidad de los picos de carbono, asi como su composicion diamond like carbón.

DLC can be considered as a metastable form of carbon material covering the spectrum between diamond and graphite. But unlike crystalline graphite or diamond, which consists of 100% sp² and 100% sp³, respectively, hybridized carbon atoms, DLC films have a mixture of sp³ and sp²  bonding and are generally amorphous, due to the lack of a long range.

diamondLike carbon qian1999.pdf

High intensity femtosecond laser deposition of diamond-like carbon thin films
F. Qian, V. Craciun, R. K. Singh, S. D. Dutta, and P. P. Pronko
Citation: Journal of Applied Physics 86, 2281 (1999); doi: 10.1063/1.371043
View online: http://dx.doi.org/10.1063/1.371043

Raman spectra (different proportion of sp2 and sp3)

El coeficiente Id/Ig muestra una estuctura diamante pedominante, además el grueso de los picos de D y G muestran tamanos de grano de :

Y la probable presencia de hojuelas de grafeno